The overall objective of this proposal is to study the living mammalian renal microcirculation which is prepared by a transplantation technique. Observations will be made under normal conditions and under conditions in which the renal circulation is known or believed to be altered. Particular attention will be given to determining; (1) the extent to which structural and vascular reactivity alterations occur in the afferent and efferent arteriole and permeability changes in the glomerular capillaries of the renal transplant when hypertension is induced in the recipient, (2) the extent to which the observed changes are reversed when the hypertension is reversed by anti-hypertensive agents, and (3) the effect of inducing acute renal failure in the recipient on the microcirculation of the transplant. Long term, we propose to transplant other tissues (myocardial, cerebral, etc.) in order to characterize them in the same manner as proposed for renal tissue.